District of Columbia truck and bus safety demonstration project. Final report.

National Highway Traffic Safety Administration, Office of State Vehicle Programs, Washington, D.C.

Mathematical recreations and problems of past and present times.

Some arithmetical questions.--Some geometrical questions.--Some mechanical questions.--Some miscellaneous questions.--Magic squares.--Unicursal problems.--Three geometrical problems.--Astrology.--Hyper-space.--Time and its measurement.--The constitution of matter.